Closed loop means complete recycling. Crops that go to feed humans are then lost as the phosphorous and other elements are dispersed elsewhere instead of being returned to the soil.

And how many people does he feed with his 5000 acres?

Can he provide enough for 100% of the daily caloric needs of 5000 people? 10,000? 100,000?

Crops and livestock require potassium. He harvests the crops and removes them (and the potassium in them) from his farm. Where does he get potassium after it's all been mined out of his soil?

I thought some of the fungi break down minerals from rocks?

There are no rocks in fields that have been cultivated for generations. Well, deep in the soil there are, but you won't find fungi down there.

Chicken manure is high in nitrogen, phosphorus, and potassium. By moving his birds behind his cattle, he is adding nutrients back into the soil that are being used by the crops that are grown afterwards. On top of that, the birds are scratching and spreading the cow manure which are full of other nutrients that are being removed by crops.

Again. The chicken and cows and the crops get eaten by humans. Phosphorous and potassium goes somewhere else, certainly not back into the farm where it originated.

It doesn't matter if the cows and the chicken do all these things, because humans aren't returning their fair share to the soil.

I saw some another video where the claim was that there’s already enough elements in the soil to last thousands of years, but they require the right mixture of microorganisms to become available to the plants. It’s only the lack of microorganisms that forces us to add those nutrients.

[0] https://youtu.be/x2H60ritjag

Yes, right, that claim is that made in a video by Dr. Elaine Ingham, called The Roots of Your Profits, which I mentioned in this same thread, here:

https://news.ycombinator.com/item?id=26718277

and which links to a comment by me (in a previous HN thread on no-till) about her work and revolutionary conclusions. And her company, Soil Food Web, is set up to consult on implementing the findings of her work.

And some major reasons both the number and diversity of microorganisms such as bacteria and fungi (and also other organisms such as archea, nematodes, arthropods) are low, is because tilling fields, not keeping the soil covered at all times as happens in nature (see Gabe Brown [1] videos where he keeps stressing how key this is and why), use of tractors, synthetic fertilizers, pesticides and fungicides depletes the soil of parameters needed for survival by those creatures, such as right moisture and temperature ranges, and organic matter levels. Not to mention the soil erosion and water body eutrophication ( https://en.m.wikipedia.org/wiki/Eutrophication ) and desertification that occurs over the years due to all these wrong practices.

All in all, it's a deadly cocktail, and the exact opposite of how nature works.

[1] Google Gabe Brown videos. He has videos, charts, stats, etc. for almost all claims he makes, claims about his neighbors' poor results compared to his, and about his performance vs. state and US averages. He has a standing invitation for any one to visit his ranch and roam around and verify his claims.